Bird nest 947038 223359995 2008-07-03T19:07:43Z DOI bot 6652755 Citation maintenance. Formatted: title. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. [[Image:Acrocephalus arundinaceus nest.jpg|thumb|right|Deep cup nest of the [[Great Reed-warbler]]]] A '''bird nest''' is the spot in which a [[bird]] lays and [[Avian incubation|incubates]] its [[egg (biology)|eggs]] and raises its young. While the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the [[American Robin]] or [[Eurasian Blackbird]], or the elaborately woven hanging nest of the [[Montezuma Oropendola]], the [[Village Weaver]] or the [[Red-browed Pardalote]]—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, or a mud dome with an entrance tunnel. Some species of [[Cave Swiftlet|cave swiftlets]] of the genus ''[[Collocalia]]'' make their nests entirely from their saliva, which dries and hardens to form a bracket on the cave wall into which the birds lay their eggs. The smallest bird nests are those of some [[hummingbird]]s, tiny cups which can be a mere 2&nbsp;[[Centimetre|cm]] (less than one [[inch]]) across and 2–3&nbsp;cm (about one inch) high.<ref name="Campbell386">{{Harvnb|Campbell|Lack|1985|p=386}}</ref> At the other extreme, some nest mounds built by the [[Dusky Scrubfowl]] measure more than 11&nbsp;[[meter|m]] (34&nbsp;[[foot (measurement)|ft]]) in diameter and stand nearly 5&nbsp;m (15&nbsp;ft) tall.<ref>{{Harvnb|Campbell|Lack|1985|p=345}}</ref> In most species, the female does all or most of the nest construction, though the male often helps.<ref>{{Harvnb|Campbell|Lack|1985|p=387}}</ref> In some [[Polygynous#Animal polygyny|polygynous]] species, however, the male may do most or all of the nest building. The nest may also form a part of their courtship display such as in [[bowerbird]]s and [[Ploceidae|weaver birds]]. The ability to choose and maintain good nest sites and build high quality nests may be selected for by females in these species. In some species the young from previous broods may also act as [[Helpers at the nest|helpers]] for the adults. ==Nest types== [[Image:Uria lomvia1.jpg|thumb|left|[[Thick-billed Murre]]s lay their single eggs directly onto rock ledges.]] Not every bird species builds or uses a nest. Some [[auk]]s, for instance—including [[Common Murre]], [[Thick-billed Murre]] and [[Razorbill]]—lay their eggs directly onto the narrow rocky ledges they use as breeding sites.<ref name = Handbook>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|pp=228-232}} </ref> The eggs of these species are dramatically pointed at one end, so that they roll in a circle when disturbed. This is critical for the survival of the developing eggs, as there are no nests to keep them from rolling off the side of the cliff. Presumably because of the vulnerability of their unprotected eggs, parent birds of these auk species rarely leave them unattended.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=692}}</ref> [[King Penguin|King]] and [[Emperor Penguin]]s also do not build nests; instead, they tuck their eggs and chicks between their feet and folds of skin on their lower bellies. They are thus able to move about while incubating, though in practice only the Emperor Penguin regularly does so. Emperor Penguins breed during the harshest months of the [[Antarctic]] winter, and their mobility allows them to form huge huddled masses which help them to withstand the extremely high winds and low temperatures of the season. Without the ability to share body heat (temperatures in the center of tight groups can be as much as 10C above the ambient air temperature), the penguins would expend far more energy trying to stay warm, and breeding attempts would probably fail.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=148}}</ref> Some crevice-nesting species, including [[Ashy Storm-petrel]], [[Pigeon Guillemot]], [[Eurasian Eagle-Owl]] and [[Hume's Tawny Owl]], lay their eggs in the relative shelter of a crevice in the rocks or a gap between boulders, but provide no additional nest material.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=252}}</ref><ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=260}}</ref> [[Potoo]]s lay their single egg directly atop a broken stump, or into a shallow depression on a branch—typically where an upward-pointing branch died and fell off, leaving a small scar or knot-hole.<ref>{{Harvnb|Cohn-Haft|1999|p=295}}</ref> [[Brood parasite]]s, such as the [[New World]] [[cowbird]]s, the [[honeyguide]]s, and many of the [[Old World]] and [[Australasian]] [[cuckoo]]s, do not build nests at all, but rather lay their eggs in the active nests of other species.<ref>{{Harvnb|Jaramillo|2001|p=548}}</ref><ref>{{Harvnb|Short|Horne|2002b|p=282}}</ref> ===Scrape=== [[Image:Gniazdo sieweczki RB.JPG|thumb|right|Shell-lined scrape nest of a ''[[Charadrius]]'' [[plover]]]] The simplest nest construction is the '''scrape''', which is merely a shallow depression in soil or vegetation.<ref>{{Harvnb|Campbell|Lack|1985|p=390}}</ref> This nest type, which typically has a rim deep enough to keep the eggs from rolling away, is sometimes lined with bits of [[vegetation]], small [[rock (geology)|stone]]s, [[seashell|shell]] fragments or [[feather]]s.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=xxii}}</ref> These materials may help to camouflage the eggs or may provide some level of insulation; they may also help to keep the eggs in place, and prevent them from sinking into muddy or sandy soil if the nest is accidentally flooded.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=441}}</ref> [[Ostrich]]es, most [[tinamou]]s, many [[duck]]s, most [[shorebird]]s, most [[tern]]s, some [[falcon]]s, [[pheasant]]s, [[quail]], [[partridge]]s, [[bustard]]s and [[sandgrouse]] are among the species that build scrape nests. Eggs and young in scrape nests&mdash;and the adults that [[incubate|brood]] them&mdash;are more exposed to [[predator]]s and the [[weather|elements]] than those in more sheltered nests; they are on the ground and typically in the open, with little to hide them. The eggs of most ground-nesting birds (including those that use scrape nests) are cryptically colored to help camouflage them when the adult is not covering them; the actual color generally corresponds to the substrate on which they are laid.<ref>{{Harvnb|Campbell|Lack|1985|p=174}}</ref> Brooding adults also tend to be well camouflaged, and may be difficult to flush from the nest. Most ground-nesting species have well-developed [[distraction display]]s, which are used to draw (or drive) potential predators from the area around the nest.<ref>{{Harvnb|Campbell|Lack|1985|p=145}}</ref> Most species with this type of nest have [[precocial]] young, which quickly leave the nest upon hatching. [[Image:Pluvialis dominica eggs and nest.jpg|thumb|left|Lichen-lined scrape nest of the [[American Golden-Plover]]]] The technique used to construct a scrape nest varies slightly depending on the species. Beach-nesting terns, for instance, fashion their nests by rocking their bodies on the [[sand]] in the place they have chosen to site their nest,<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=637}} </ref> while [[skimmers]] build their scrapes with their feet, kicking sand backwards while resting on their bellies and turning slowly in circles.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=673}}</ref> The Ostrich also scratches out its scrape with its feet, though it stands while doing so.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=80}}</ref> Many tinamous lay their eggs on a shallow mat of dead [[leaves]] they have collected and placed under [[shrub|bush]]es or between the [[root]] buttresses of [[tree]]s,<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=119}}</ref> and [[Kagu]]s lay theirs on a pile of dead leaves against a log, tree trunk or vegetation.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=222}}</ref> [[Marbled Godwit]]s stomp a grassy area flat with their feet, then lay their eggs, while other grass-nesting waders bend vegetation over their nests so as to avoid detection from above.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=473}}</ref> Many female ducks, particularly in the [[north]]ern [[latitude]]s, line their shallow scrape nests with down feathers plucked from their own breasts, as well as with small amounts of vegetation.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1992|p=558}}</ref> Among scrape-nesting birds, the [[Three-banded Courser]] and [[Egyptian Plover]] are unique in their habit of partially burying their eggs in the sand of their scrapes.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=371}}</ref> ===Mound=== [[Image:Malleefowl mound.jpg|Mound nest of the [[Malleefowl]]|thumb|right]] Burying eggs as a form of incubation reaches its zenith with the [[Australiasia]]n [[megapode]]s. Several megapode species construct enormous '''mound''' nests made of soil, branches, sticks, twigs and leaves, and lay their eggs within the rotting mass. The heat generated by these mounds, which are in effect giant compost heaps, warms and incubates the eggs.<ref name="Campbell386"/> Recent research has shown that much of the nest's heat results from the respiration of thermophilic [[fungi]] and other [[microorganism]]s rather than fermentation, as had been previously believed.<ref name="HBW2-287"/> The size of some of these mounds can be truly staggering; several of the largest&mdash;which contain more than 100 cubic meters of material, and probably weigh more than 50 tons<ref name="HBW2-287">{{Harvnb|Elliott|1994|p=287}}</ref>&mdash;were initially thought to be [[Indigenous Australians|Aboriginal]] middens.<ref>{{Harvnb|Hansell|2000|p=9}}</ref> In most mound-building species, males do most or all of the nest construction and maintenance.<ref name="HBW2-288">{{Harvnb|Elliott|1994|p=288}}</ref> Using his strong legs and feet, the male scrapes together material from the area around his chosen nest site, gradually building a conical or bell-shaped pile. This process can take five to seven hours a day for more than a month.<ref name="HBW2-288"/> While mounds are typically reused for multiple breeding seasons, new material must be added each year in order to generate the appropriate amount of heat. A female will begin to lay eggs in the nest only when the mound's temperature has reached an optimal level. [[Image:Slimbridge.chilean.flamingo.arp.jpg|thumb|left|upright|[[Chilean Flamingo]]s with mound nests]] Both the temperature and the moisture content of the mound are critical to the survival and development of the eggs, so both are carefully regulated for the entire length of the breeding season (which may last for as long as eight months), principally by the male.<ref name="HBW2-287"/> Ornithologists believe that megapodes may use sensitive areas in their mouths to assess mound temperatures; each day during the breeding season, the male digs a pit into his mound and sticks his head in.<ref>{{Harvnb|Elliott|1994||p=280}}</ref> If the mound's core temperature is a bit low, he adds fresh moist material to the mound, and stirs it in; if it is too high, he opens the top of the mound to allow some of the excess heat to escape. This regular monitoring also keeps the mound's material from becoming compacted, which would inhibit oxygen diffusion to the eggs and make it more difficult for the chicks to emerge after hatching.<ref name="HBW2-288"/> The [[Malleefowl]], which lives in more open forest than do other megapodes, uses the sun to help warm its nest as well&mdash;opening the mound at midday during the cool spring and autumn months to expose the plentiful sand incorporated into the nest to the sun's warming rays, then using that warm sand to insulate the eggs during the cold nights. During hot summer months, the Malleefowl opens its nest mound only in the cool early morning hours, allowing excess heat to escape before recovering the mound completely.<ref>{{Harvnb|Elliott|1994|p=289}}</ref> One recent study showed that the sex ratio of [[Australian Brush-turkey]] hatchlings correlated strongly with mound temperatures; females hatched from eggs incubated at higher mean temperatures.<ref>{{cite journal |last= Göth |first=Anne |title= Incubation temperatures and sex ratios in Australian brush-turkey (''Alectura lathami'') mounds |journal= Austral Ecology |year= 2007 |volume= 32 |issue= 4 |pages= 278–285 |doi= 10.1111/j.1442-9993.2007.01709.x}}</ref> [[Flamingo]]s make a different type of mound nest. Using their [[beak]]s to pull material towards them,<ref name = "delHoyo516">{{Harvnb|del Hoyo|1992|p=516}}</ref> they fashion a cone-shaped pile of mud between 15&ndash;46&nbsp;cm (6&ndash;18&nbsp;inches) tall, with a small depression in the top to house their single egg.<ref>{{Harvnb|Seng|2001|p=188}}</ref> The height of the nest varies with the substrate upon which it is built; those on [[clay]] sites are taller on average than those on dry or sandy sites.<ref name = "delHoyo516"/> The height of the nest and the circular, often water-filled trench which surrounds it (the result of the removal of material for the nest) help to protect the egg from fluctuating water levels and excessive heat at ground level. In [[East Africa]], for example, temperatures at the top of the nest mound average some 20C (40F) cooler than those of the surrounding ground.<ref name = "delHoyo516"/> ===Burrow=== [[Image:Riparia riparia-Oeverzwaluw.jpg|thumb|right|[[Sand Martin]] at the entrance of its burrow nest]] Soil plays a different role in the '''burrow''' nest; here, the eggs and young&mdash;and in most cases the incubating parent bird&mdash;are sheltered under the earth. Most burrow-nesting birds excavate their own burrows, but some use those excavated by other species; [[Burrowing Owl]]s, for example, sometimes use the burrows of [[prairie dog]]s, [[ground squirrel]]s, [[badger]]s or [[tortoise]]s,<ref>{{Harvnb|Behrstock|2001|p=344}}</ref> China's endemic [[White-browed Tit]]s use the holes of ground-nesting rodents<ref>{{Harvnb|Harrap|Quinn|1996|p=21}}</ref> and [[Common Kingfisher]]s occasionally nest in rabbit burrows.<ref name = "HBW6-169">{{Harvnb|Woodall|2001|p=169}}</ref> [[Puffin]]s, [[shearwater]]s, some megapodes, [[motmot]]s, [[tody|todies]], most [[kingfisher]]s, the [[Crab Plover]], [[Geositta|miner]]s and [[Sclerurus|leaftosser]]s are among the species which use burrow nests. Most burrow nesting species dig a horizontal tunnel into a vertical (or nearly vertical) dirt cliff, with a chamber at the tunnel's end to house the eggs.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=xxiii}}</ref> The length of the tunnel varies depending on the substrate and the species; Sand Martins make relatively short tunnels ranging from 50&ndash;90&nbsp;cm (20&ndash;35&nbsp;in),<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=345}}</ref> for example, while those of the [[Burrowing Parakeet]] can extend for more than three meters (nearly 10&nbsp;ft).<ref>{{Harvnb|Juniper|Parr|2003|p=24}}</ref> Some species, including the ground-nesting [[puffbird]]s, prefer flat or gently sloping land, digging their entrance tunnels into the ground at an angle.<ref>{{Harvnb|Rasmussen|Collar|2002|p=119}}</ref> In a more extreme example, the [[D'Arnaud's Barbet]] digs a vertical tunnel shaft more than a meter (39&nbsp;in) deep, with its nest chamber excavated off to the side at some height above the shaft's bottom; this arrangement helps to keep the nest from being flooded during heavy rain.<ref>{{Harvnb|Short|Horne|2002a|p=162}}</ref> [[Buff-breasted Paradise-kingfisher]]s dig their nests into the compacted mud of active termite mounds, either on the ground or in trees.<ref name="HBW6-169">{{Harvnb|Woodall|2001|p=169}}</ref> [[Image:Merops apiaster burrows .jpg|thumb|left|Burrow entrances in [[European Bee-eater]] colony]] Birds use a combination of their beaks and feet to excavate burrow nests. The tunnel is started with the beak; the bird either probes at the ground to create a depression, or flies toward its chosen nest site on a cliff wall and hits it with its bill. The latter method is not without its dangers; there are reports of kingfishers being fatally injured in such attempts.<ref name="HBW6-169"/> Some birds remove tunnel material with their bills, while others use their bodies or shovel the dirt out with one or both feet. Female paradise-kingfishers are known to use their long tails to clear the loose soil.<ref name="HBW6-169"/> Predation levels on some burrow-nesting species can be quite high; on [[Alaska]]'s Wooded Islands, for example, [[river otter]]s munched their way through some 23 percent of the island's Fork-tailed Storm-Petrel population during a single breeding season in 1977.<ref>{{cite journal |title=The Breeding Biology of the Fork-tailed Storm-Petrel (Oceandroma Furcata) |last=Boersma |first=P. Dee |coauthors=Nathaniel T. Wheelwright, Mary K. Nerini & Eugenia Stevens Wheelwright |journal=Auk |volume=97 |number=2 |pages=268–282 |date=April 1980 |url=http://elibrary.unm.edu/sora/Auk/v097n02/p0268-p0282.pdf}}</ref> There is some evidence that increased vulnerability may lead some burrow-nesting species to form colonies, or to nest closer to rival pairs in areas of high predation than they might otherwise do.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=17}}</ref> Not all burrow-nesting species incubate their young directly. Some megapode species bury their eggs in sandy pits dug where sunlight, subterranean volcanic activity, or decaying tree roots will warm the eggs.<ref name="Campbell386"/><ref name="HBW2-287"/> ===Cavity=== [[Image:Colaptes auratus FWS.jpg|thumb|right|upright|A [[Northern Flicker]] protruding from its cavity nest]] The '''cavity''' nest is a chamber, typically in living or dead wood, but sometimes in the trunks of [[tree fern]]s<ref name="HBW6-94">{{Harvnb|Collar|2001|p=94}}</ref> or large [[cactus|cacti]], including [[Carnegiea|saguaro]].<ref name="HBW6-94"/><ref name = "WP"/> In tropical areas, cavities are sometimes excavated in arboreal insect nests.<ref>{{cite journal |last= Brightsmith |first= Donald J. |title= Use of Arboreal Termitaria by Nesting Peruvian Amazon |journal= Condor |year= 2000 |volume= 102 |pages= 529–538 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v102n03/p0529-p0538.pdf |doi= 10.1650/0010-5422(2000)102[0529:UOATBN]2.0.CO;2}} </ref><ref name = "HBW6-96">{{Harvnb|Collar|2001|p=96}}</ref> A relatively small number of species, including [[woodpecker]]s, [[trogon]]s, some [[nuthatch]]es and many [[barbets]], can excavate their own cavities. Far more species—including [[parrot]]s, [[Paridae|tit]]s, [[bluebird]]s, most [[hornbill]]s, some kingfishers, some [[true owl|owl]]s, some [[duck]]s and some [[flycatcher]]s—use natural cavities, or those abandoned by species able to excavate them; they also sometimes usurp cavity nests from their excavating owners. Those species that excavate their own cavities are known as "primary cavity nesters", while those that use natural cavities or those excavated by other species are called "secondary cavity nesters". Both primary and secondary cavity nesters can be enticed to use [[nest box]]es (also known as bird houses); these mimic natural cavities, and can be critical to the survival of species in areas where natural cavities are lacking.<ref>{{cite journal |journal=BirdScope |publisher=Cornell Laboratory of Ornithology |date=Winter 2005 |title=Nest Boxes: More than Just Birdhouses |last=Phillips |first=Tina |volume=19 |issue=1 |pages= |url=http://www.birds.cornell.edu/Publications/Birdscope/Winter2005/nest_boxes.html}}</ref> Woodpeckers use their chisel-like bills to excavate their cavity nests, a process which takes, on average, about two weeks.<ref name = "WP">{{Harvnb|Reed|2001|p=380&ndash;1}}</ref> Cavities are normally excavated on the downward-facing side of a branch, presumably to make it more difficult for predators to access the nest, and to reduce the chance that rain floods the nest.<ref name = "Conner">{{Harvnb|Conner|1975|p=373}}</ref> There is also some evidence that fungal rot may make the wood on the underside of leaning trunks and branches easier to excavate.<ref name = "Conner"/> Most woodpeckers use a cavity for only a single year. The endangered [[Red-cockaded Woodpecker]] is an exception; it takes far longer—up to two years—to excavate its nest cavity, and may reuse it for more than two decades.<ref name = "WP"/> The typical woodpecker nest has a short horizontal tunnel which leads to a vertical chamber within the trunk. The size and shape of the chamber depends on species, and the entrance hole is typically only as large as is needed to allow access for the adult birds. While wood chips are removed during the excavation process, most species line the floor of the cavity with a fresh bed of them before laying their eggs. [[Image:BlackWoods.jpg|thumb|left|[[Black Woodpecker]] youngsters in their cavity nest]] Trogons excavate their nests by chewing cavities into very soft dead wood; some species make completely enclosed chambers (accessed by upward-slanting entrance tunnels), while others—like the extravagantly-plumed Resplendent Quetzal—construct more open niches.<ref name="HBW6-96"/> In most trogon species, both sexes help with nest construction. The process may take several months, and a single pair may start several excavations before finding a tree or stump with wood of the right consistency. Species which use natural cavities&mdash;or old woodpecker nests&mdash;sometimes line the cavity with soft material such as grass, moss, lichen, feathers or fur. Though a number of studies have attempted to determine whether secondary cavity nesters preferentially choose cavities with entrance holes facing certain directions, the results remain inconclusive.<ref name="Rendell">{{Harvnb|Rendell|Robertson|1994|pp=27-35}}</ref> While some species appear to preferentially choose holes with certain orientations, studies (to date) have not shown consistent differences in fledging rates between nests oriented in different directions.<ref name = "Rendell"/> Cavity-dwelling species have to contend with the danger of predators accessing their nest, catching them and their young inside and unable to get out. They have a variety of methods for decreasing the likelihood of this happening. Red-cockaded Woodpeckers peel bark around the entrance, and drill wells above and below the hole; since they nest in live trees, the resulting flow of resin forms a barrier that prevents snakes from reaching the nests.<ref>{{harvnb|Rudolph|Kyle|Conner|1990}}</ref> [[Red-breasted Nuthatch]]es smear sap around the entrance holes to their nests, while [[White-breasted Nuthatch]]es rub foul-smelling insects around theirs.<ref>{{Harvnb|Reed|2001|p=437}}</ref> [[Eurasian Nuthatch]]es wall up part of their entrance holes with mud, decreasing the size and sometimes extending the tunnel part of the chamber. Most female hornbills seal themselves into their cavity nests, using a combination of mud (in some species brought by their mates), food remains and their own droppings to reduce the entrance hole to a narrow slit.<ref>{{Harvnb|Kemp|2001|p=469}}</ref> ===Cup=== [[Image:Redwing nest.jpg|thumb|right| Cup nest of a [[Redwing]], with newly hatched chicks]] The '''cup''' nest is smoothly hemispherical inside, with a deep depression to house the eggs. Most are made of pliable materials—including grasses—though a small number are made of mud. Many [[passerine]]s and a few non-passerines, including some [[hummingbird]]s and some swifts, build this type of nest. Small bird species in more than 20 passerine families, and a few non-passerines—including most hummingbirds, kinglets and crests in the genus ''[[Regulus (genus)|Regulus]]'', some [[tyrant flycatcher]]s and several [[New World warbler]]s—use considerable amounts of spider silk in the construction of their nests.<ref>{{Harvnb|Ehrlich|Dobkin|WHeye|Pimms|1994|p=445}}</ref><ref name=Erickson>{{cite journal |last=Erickson |first=Laura |title=The Wonders of Spider Silk |journal=BirdScope |date=Spring 2008 |volume=22 |issue=2 |pages=7}}</ref> The lightweight material is strong and extremely flexible, allowing the nest to mold to the adult during incubation (reducing heat loss), then to stretch to accommodate the growing nestlings; as it is sticky, it also helps to bind the nest to the branch or leaf to which it is attached.<ref name=Erickson/> ===Saucer or plate=== The '''saucer''' or '''plate''' nest, though superficially similar to a cup nest, has at most only a shallow depression to house the eggs. ===Platform=== [[Image:Osprey landing in the nest at Camp Echockotee.JPG|thumb|right|The huge platform nest of the [[Osprey]]]] The '''platform''' nest is a large structure, often many times the size of the birds which build and use it. In the case of raptor nests, or eyries, these are often used for many years, with new material added each breeding season. In some cases, the nests grow large enough to cause structural damage to the tree itself, particularly during bad storms where the weight of the nest can cause additional stress on wind-tossed branches. ===Pendant=== [[Image:Taveta Golden-weaver nest.JPG|thumb|right|[[Taveta Golden Weaver]] building pendant nest]] The '''pendant''' nest is an elongated sac woven of pliable materials such as grasses and plant fibers and suspended from a branch. [[Oropendola]]s, [[cacique]]s, [[oriole]]s, [[weaver]]s and [[sunbird]]s are among the species that weave pendant nests. ===Sphere=== The '''sphere''' nest is a roundish structure; it is completely enclosed, except for a small opening which allows access. ==Nest protection and sanitation== Many species of bird conceal their nests to protect them from predators. Some species may choose nest sites that are inaccessible. Some may make specific modifications to keep predators at bay. Bird nests can also act as habitats for other [[inquiline]] species which may not affect the bird directly. Birds have also evolved nest sanitation measures to reduce the effects of parasites and pathogens on nestlings. Some aquatic species such as Grebes are very careful when approaching and leaving the nest so as not to reveal the location. Some species will use leaves to cover up the nest prior to leaving. Ground birds such as plovers may use ''broken wing'' or ''rodent run'' displays to distract predators from nests.<ref>{{harvnb|Byrktedal|1989}}</ref> Nests can become home to many other organisms including parasites and pathogens. The excreta of the fledglings also pose a problem. In most passerines, the adults actively dispose the fecal sacs of young at a distance or consume them. This is believed to help prevent ground predators from detecting nests.<ref>{{harvnb|Petit|Petit|Petit|1989}}</ref> Young birds of prey however usually void their excreta beyond the rims of their nests.<ref>{{harvnb|Rosenfeld|Rosenfeld|Gratson|1982}}</ref> [[calliphoridae|Blowflies]] of the genus ''[[Protocalliphora]]'' have specialized to become obligate nest parasites with the maggots feeding on the blood of nestlings.<ref>{{harvnb|Sabrosky|Bennett|Whitworth|1989}}</ref> Some birds have been shown to choose aromatic green plant material for constructing nests that may have insecticidal properties, <ref>{{harvnb|Wimberger|1984}}</ref><ref>{{harvnb|Clark|Mason|1985}}</ref> while others may use materials such as carnivore scat to repel smaller predators.<ref>{{harvnb|Schuetz|2005}}</ref> [[Image:PMontezumaNests03.jpg|thumb|Nesting colony of [[Montezuma Oropendola]]s]] ==Colonial nesting== {{main|Bird colony}} Though most birds nest individually, some species&mdash;including [[seabird]]s, [[penguin]]s, flamingos, many [[heron]]s, [[gull]]s, [[tern]]s,[[weaver]]s, some [[corvid]]s and some [[sparrow]]s&mdash;gather together in sizeable colonies. Birds that nest colonially may benefit from increased protection against predation. They may also be able to better utilize food supplies, by following more successful foragers to their foraging sites.<ref>{{Harvnb|Ward|Zahavi|1973}}</ref> ==In human culture== Many birds nest close to human habitations and some have been specially encouraged. Nesting [[White Stork]]s have been protected and held in reverence in many cultures.<ref>{{cite journal |last=Kushlan |first=James A. |year=1997 |title=The Conservation of Wading Birds |journal=Colonial Waterbirds |volume=20 |issue=1 |pages=129–137 |doi=10.2307/1521775}}</ref> [[Nest box]]es are often used to encourage cavity nesting birds. The nesting of [[Peregrine Falcon]]s on tall buildings has captured popular interest.<ref>{{harvnb|Cade|Bird|1990}}</ref> Colonial breeders produce [[guano]] which is a valuable fertilizer. The saliva nests of [[Swiftlet|Cave Swiftlets]] are used to make [[Bird's nest soup]] in parts of [[Southeast Asia]]. Some species of birds are also considered nuisances when they nest in the proximity of human habitations. Feral pigeons are often unwelcome and sometimes also considered as a health risk.<ref>{{harvnb|Haag-Wackernagel|Moch|2004}}</ref> The [[Beijing Olympic Stadium]], principal venue of the [[2008 Summer Olympics]], has been nicknamed "The Bird Nest" because of its architectural design, which its designers likened to a bird's woven nest.<ref>{{cite web |url= http://www.bjghw.gov.cn/forNationalStadium/indexeng.asp#11 |title= Competition entries for design of Beijing National Stadium |publisher=Beijing Municipal Commission of Urban Planning |accessdate=2008-02-25}}</ref> ==Sources== ===Citations=== {{reflist|3}} ===References=== <div class="references-small"> *{{citation |last= Behrstock |first= Robert A. |editor-last= Elphick |editor-first= Chris |editor2-last= Dunning, Jr. |editor2-first= John B. |editor3-last= Sibley |editor3-first= David |contribution= Typical Owls |title= The Sibley Guide to Bird Life & Behaviour |publisher= Christopher Helm |location= London |year=2001 |isbn= 0-7136-6250-6}} *{{citation|last=Byrktedal|first=Ingvar|year=1989|title= Nest defense behavior of Lesser Golden-Plovers|journal=Wilson Bull.|volume=101|issue=4|pages=579–590|url=http://elibrary.unm.edu/sora/Wilson/v101n04/p0579-p0590.pdf}} *{{citation|last1=Cade|first1=T.J.|last2=Bird|first2=D.M.|year=1990|title=Peregrine Falcons (''Falco peregrinus'') nesting in an urban environment: a review|journal=Can. 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